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menaquinone (Vitamin K2) Enhancement of <i>Staphylococcus aureus</i>Biofilm Formation

Journal of Biosciences and Medicines 2014年第1期2卷 26-32页

作者： Derek T. Kirby Joyce M. Savage Balbina J. Plotkin Department of Microbiology and Immunology Midwestern University Downers Grove USA

During infection, Staphylococcus aureus is exposed to exogenous menaquinone which is essential for the human blood clotting cascade. The effect of exogenous menaquinone on S. aureus phenotypic expression is not known. To test whether menaquinone affects expression of virulence-associated phenotypes, methicillin-sensitive (MSSA) and -resistant (MRSA) S. aureus strains (n = 8) were grown in the presence of menaquinone (0.001 - 12 μg/ml). Capsule production, biofilm formation (plastic and fibronectin-coated microtiter plates) and carotenoid levels were determined spectrophotometrically after growth in Mueller Hinton broth (MH;24-hr, 37°C). All experiments were, at minimum, done in triplicate and repeated twice. menaquinone at physiologic levels (0.01 μg/ml MH) significantly increased (p 0.05) biofilm formation on plastic in a manner that was bacterial population size dependent. In addition, menaquinone (0.05 - 4 μg/ml) significantly increased (p 0.05) biofilm formation on fibronectin-coated surfaces for four MSSA strains and one MRSA strain by two to six-fold as compared to medium controls. However, menaquinone had no effect on capsule production or cell-associated carotenoid levels. menaquinone’s effect on biofilm formation on fibronectin-coated surfaces appears to be regulated by sarA. These findings are the first to demonstrate that a vitamin at concentrations reported in humans affects S. aureus virulence-associated phenotypes.

关键词： Quorum S. aureus menaquinone Fibronectin Biofilm Capsule Plastic Adherence Carotenoid

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Characterization of 1,4-dihydroxy-2-naphthoyl-coenzyme A synthase(MenB) in phylloquinone biosynthesis of Synechocystis *** 6803

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Science China Chemistry 2012年第1期55卷 98-105页

作者： SONG HaiGang GUO ZhiHong Department of Chemistry and State Key Laboratory for Molecular Neuroscience The Hong Kong University of Science and Technology Clear Water Bay Hong Kong SAR China

The gene product Sll1127 is a predicted 1,4-dihydroxy-2-naphthoyl-CoA synthase catalyzing an intramolecular Claisen condensation in the phylloquinone biosynthesis of the cyanobacterium Synechocystis *** *** predicted catalytic function has been verified and the enzyme has been characterized for the first time with kcat = 0.013 s-1 and KM = 9μ*** catalytic activity is found to strictly depend on externally added bicarbonate with an apparent KD = 0.60 *** addition,this enzyme is inhibited by its 1,4-dihydroxy-2-naphthoyl-CoA product through high-affinity binding,which causes a 18 nm shift of the inhibitor absorption at 392 to 410 nm and engenders a new absorption peak at 345 *** these properties of the cyanobacterial enzyme are closely similar to those of the Escherichia coli orthologue from the menaquinone biosynthetic *** results provide additional supporting evidence for the essential role of bicarbonate as a catalytic base in the enzymatic reaction and the eubacterial origin of the enzymes in the cyanobacterial biosynthesis of phylloquinone.

关键词： DHNA-CoA synthase bicarbonate cofactor phylloquinone menaquinone biosynthesis

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AM1 and ab initio studies on the internal reorganization energy of self-exchange electron transfer reactions of several quinone derivatives

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Chinese Science Bulletin 2001年第15期46卷 1242-1251页

作者： Shuhua Ma Xiaodong Zhang Hong Xu Xingkang Zhang Qiyuan Zhang State Key Laboratory for Structural Chemistry of Unstable & Stable Species Center of Molecular Science Institute of Chemistry Chinese Academy of Sciences Beijing China

The semiempirical AMI method, ah initio (HF/3-21G, 6-31G, 6-31G(d), 6-31+G(d)) and DFT (B3LYP/6-31G(d), 6-31+G(d)) methods were used to optimize the geometry of DDQ and its anion radical DDQ-. Nelsen’s model was used to calculate the internal reorganization energy λi of self-exchange electron transfer (ET) reactions. The calculated λi results of DDQ/DDQ-. by AM1 and B3LYP/ 6-31G(d), 6-31+G(d) methods are close to each other and consistent with the reported values; while those from Har-tree-Fock methods are too large because of not consideringthe effect of electron correlation. The structure and ET behavior of MQ0 /MQ0- couple were studied by AM1 and DFT (B3LYP/6-31G(d), 6-31+ G(d, p)) methods, and those of MQ0 /MQn-(n=1-7) were studied by AM1 method for the first time. The results indicate that the values of the heat of formation of MQn increases with the increasing of the length of the isoamylene substituent chains. It also shows that the length of substituent has little effect on the bond lengths,

关键词： DDQ menaquinone (MQn) self-exchange electron transfer internal reorganization energy AM1 ab initio DFT.

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Semi-Automated Method for Multi-Tasking Measurement of Microbial Growth, Capsule, and Biofilm Formation

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Advances in Microbiology 2012年第4期2卷 623-628页

作者： Derek T. Kirby Craigory J. Raino Samuel F. Rabor Jr. Cassandra J. Wasson Balbina J. Plotkin Department of Microbiology and Immunology Midwestern University Downers Grove USA Department of Microbiology and Immunology Midwestern University Downers Grove USA

The majority of bacterial infections involve the formation of biofilms. Biofilm formation is nutrient and growth dependent. Determination of the effects of nutrients on exopolysaccharide production and bacterial growth is labor and time intensive. We tested whether the Bioscreen C (Growth Curves, Inc.) would have utility as a high-throughput tool in the measurement of fundamental phenotype expression, as it relates to growth conditions. Within 48 - 72 hr, reproduceble, statistically significant data on the affects of growth conditions on generation time, capsule production and biofilm formation (maximally for 25 different conditions per 24 hr run cycle;n = 4) were obtained. Although all S. aureus strains produced similar amounts of capsule, sarA– and agr– strains grew significantly slower than parent strain (1.6 fold slower) and produced significantly (p 0.05) less biofilm (~2 fold). E. coli growth rate, biofilm and capsule production in simulated nephropathic urine medium was similar for urine with insulin (20 μU). Addition of insulin to urine medium with proline increased generation time, capsule and biofilm production. Findings from this study show that the Bioscreen C is a rapid, reproducible, and easily manipulated system to concurrently measure bacterial growth, biofilm formation, and capsule production. In addition, there is the potential for further applications of this system by expanding the types of detector dyes used.

关键词： Biofilm Staphylococcus aureus Escherichia coli Quorum-Signaling Compounds menaquinone Insulin Growth

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